Prime Minister Stephen Harper speaks with Chilean President Michelle Bachelet at the APEC summit on Saturday. (Adrian Wyld/Canadian Press)

U.S. President Barack Obama and nearly two dozen fellow leaders from Canada, Asia and Europe at an APEC summit in Singapore agreed Sunday that next month's international climate change meetings will be a way station — not the end point — in the so-far elusive search for a new worldwide treaty to tackle global warming.

The 192-nation climate conference beginning in three weeks in Copenhagen had originally been intended to produce a new global climate change treaty. More recently, it has become increasingly clear that wouldn't be the case.

On Saturday, Prime Minister Stephen Harper who is attending the APEC summit, said that full global participation in cutting greenhouse gases is necessary to tackle global warming.

Emerging economies already contribute close to half of all global emissions, and that proportion will rise to two-thirds in the future, he told reporters.

"If we don't control those, whatever we do in the developed world will have no impact on climate change," Harper said.

Prof. Tim Flannery of the Copenhagen Climate Council, also in Singapore for the summit of the Asia-Pacific Economic Co-operation countries, delivered a harsh assessment of Canada's record on reducing emissions.

Flannery told The Canadian Press that Canada faces an international credibility crisis because it is "by far the biggest defaulter" on previous Kyoto Protocol obligations.

He said even though Canada signed on 11 years ago, it has failed to meet its obligations.

"The people of Canada, through their government, made the commitment, and it needs to be honoured somehow or other, or it needs to be dealt with," the Australian climate-change expert said.

Prime Minister Stephen Harper and his wife Laureen chat with U.S. President Barack Obama on Saturday. (PMO/Jason Ransom)

"Canada is by far the biggest defaulter on its Kyoto obligations on a tonnage basis. And as a result of that there is a lack of trust," he said.

The APEC summit comes less than a month before a United Nations climate change conference opens in Copenhagen, where leaders of almost 200 countries will gather to hash out a successor to the Kyoto Protocol.

Harper acknowledged there are "significant differences" over how to tackle climate change, but he said every leader he's spoken to at the summit agrees on the need for a long-term plan to curb greenhouse gas emissions.

When it comes to the economy, the prime minister is pushing for a reduction of trade barriers, in light of the global recession.

David Emerson, Canada's former minister for international trade, told CBC News that in the 21st century, environmental issues cannot be separated from economic and trade issues "because they're becoming increasingly intertwined."

Canada needs to get more pro-active on boosting trade with emerging economies, including having a physical presence in those countries, which means direct investment, Emerson said.

"It means moving people into those markets… it means cultural knowledge and adaptation and fluency with language," he said in an interview on CBC's The National on Saturday.

"It's a much different game today and it's going to take a much broader, deeper, more comprehensive effort for Canada to get back in the game in the way we should be."

nations need not fear the success of another," Obama said. "Cultivating spheres of co-operation — not competing spheres of influence — will lead to progress in the Asia Pacific."

With files from The Canadian Press